With the engines having been started in the car for the first time at DRA, Farnborough, over the weekend of 10th and 11th August, and successful runs up to ‘idle’ speed achieved with both of the Rolls-Royce Speys installed in ThrustSSC, it was now time to begin testing the car under higher power.

After Sunday’s successful test, ThrustSSC was loaded onto its trailer, ready to make the journey early the next morning to DTEO Boscombe Down. Using the tie-down test cell there, the objective of the test was to run the two Spey 202s up to maximum power to prove the onboard car systems and the durability of the rear fuselage under the extremes of heat and acoustic vibration from the engines in reheat.

(The ThrustSSC Scanias. Photo: Jeremy Davey)

At 5am Q Shed was bustling with life as the final preparations were made for the journey to Wiltshire. A Supacat support vehicle and ‘dolly’ were loaded on a flatbed to go with one of the Scania tractor units, with the other Scania being hitched to Thrust SSC’s specially built trailer. Before 7 am had arrived, the team were on their way through the heavy clouds and drizzle that had returned again to Farnborough. The weather brightened as Boscombe Down approached, finally breaking out into a warm, sunlit day - indeed by the end of afternoon more than one team member would have caught a little too much sun.

(Thrust SSC awaits tests. Photo: Jeremy Davey)

The media were awaiting the car’s arrival, such is the interest now being shown in the project, and after the vehicles had been unloaded, swarmed around the car admiring the magnificent lines. The test cell at Boscombe Down is a superb facility, with a shaped rear wall to deflect the blast of military jet engines on full reheat, and tall walls on either side which were quickly surmounted by the photographers. A load cell was affixed to the thick cable securing the car, and a display set up to show the thrust being generated by the Speys.

(Al Harkness conducting left-hand engine test. Photo: Jeremy Davey)

Al Harkness was in charge of the test, and began by running the team through the plan of action, followed by a safety briefing for the visitors. The two start teams then set to work: first was a run of the left-hand engine to 70% of maximum revolutions. The air-starter, or ‘Palouste’ was wound up, giving a mere taste of the noise to come - but nevertheless emphasising the need for ear defenders to be worn. The air line was attached and the signal given to turn the engine over. Over the rumble of the Palouste came the whine of a Spey turbine accelerating, and with fuel and ignition applied it quickly rose to a roar, with a haze of smoke drifting over the car from the remains of the engine’s protective inhibitor oil. The load cell started to give a reading, reaching over 3000 lbs of thrust.

(Boscombe Down engine test cell. Photo: Jeremy Davey)

It may not have been possible to hold a conversation, but it was obvious that the attendant media were impressed by the sheer power leashed in the test cell below them. Next came the right-hand engine, and with more smoke and acrid exhaust it, too, burst into life. Having settled down well, both engines were shut down, and peace settled again on Boscombe Down. With more fuel added to the car’s tanks it was time to start the next test - up to ‘Max MIL’ or full power without reheat. The left-hand engine was started and power increased slowly until it stabilised at 95% of maximum revolutions - the load cell was reading over 11,000lbs of thrust. Then the Spey experienced a surge and was quickly shut down to prevent it from doing itself any harm.

(Al Harkness and Andy Green discuss progress. Photo: Jeremy Davey)

Having discussed the test the team then went for Max MIL on the right-hand engine. It too stabilised at 95%, and then surged. It was obvious to the engine team that the surges were intake-induced - being due to the extreme test of running full power on the engines while the car was stationary - something which would not happen under running conditions when the car would be accelerating hard with air being forced into the intakes by the forward motion of the car above 100 mph.

(Boscombe Down engine test cell. Photo: Jeremy Davey)

The problem was not one that could be solved on the spot, so the team elected to return to Farnborough, evaluate the situation and make appropriate modifications to the car, if necessary, before returning to Boscombe Down to complete the tests. The Scanias were brought up again and ThrustSSC and the support equipment reloaded and returned to base. Tomorrow the team will meet to finalise any changes to be made in conjunction with the intake designer and the Rolls-Royce and RAF engine specialists - we will, of course, bring you the news on the Internet in the next day or so.

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